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volume; 6 
OCTOBER, 1920 
PROCEEDINGS 
OF THE 
NUMBER 10 
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National Academy 
OF Sciences 
OF THE 
UNITED STATES OF AMERICA 
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EDITORIAL BOARD 
Raymond Peari., Chairman Edwin B. Wilson, Managing Editor 
C. G. Abbot, Home Secretary ^ George E. Hale, Foreign Secretary 
J. M. Clarke 
A. L. Day 
Gano Dunn 
E. B. Frost 
LUDVIG Hektoen 
L. J. Henderson 
H. S. Jennings 
Jacques Loeb 
J. C. Merriam 
R. A. Millikan 
PUBLISHED MONTHLY 
E. H Moore 
W. A. NoYES 
W. J. V. Osterhout 
E. L. Thorndike 
W. M. Wheeler 
Publication Office: Eschenbach Printing Company, Easton, Pa. 
Editorial Office : Massachusetts Institute of Technology, Cambridge 
Home Office of the Academy: Washington, D. C. 
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Entered as second-class matter June 21, 1920, at the postofEce at Easton, Pennsylvania, under the act of August 24, 1912. 
Acceptance for mailing at special rate of postage provided for in Section 1103, Act of October 3, 1917. Authorizted June 18, 1920. 
Price per annum, $5.00 
